Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M141/00—Lubricating compositions characterised by the additive being a mixture of two or more compounds covered by more than one of the main groups C10M125/00 - C10M139/00, each of these compounds being essential
  • C10M141/02—Lubricating compositions characterised by the additive being a mixture of two or more compounds covered by more than one of the main groups C10M125/00 - C10M139/00, each of these compounds being essential at least one of them being an organic oxygen-containing compound
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M121/00—Lubricating compositions characterised by the thickener being a compound of unknown or incompletely defined constitution
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M125/00—Lubricating compositions characterised by the additive being an inorganic material
  • C10M125/06—Sulfur
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
  • C10M169/06—Mixtures of thickeners and additives
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
  • C10M2201/04—Elements
  • C10M2201/041—Carbon; Graphite; Carbon black
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
  • C10M2201/04—Elements
  • C10M2201/041—Carbon; Graphite; Carbon black
  • C10M2201/0416—Carbon; Graphite; Carbon black used as thickening agents
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
  • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
  • C10M2203/1006—Petroleum or coal fractions, e.g. tars, solvents, bitumen used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
  • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
  • C10M2205/026—Butene
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
  • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
  • C10M2205/028—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers containing aliphatic monomers having more than four carbon atoms
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
  • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
  • C10M2205/028—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers containing aliphatic monomers having more than four carbon atoms
  • C10M2205/0285—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers containing aliphatic monomers having more than four carbon atoms used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/10—Carboxylix acids; Neutral salts thereof
  • C10M2207/12—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms
  • C10M2207/125—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids
  • C10M2207/126—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids monocarboxylic
  • C10M2207/1265—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids monocarboxylic used as thickening agent
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
  • C10M2209/02—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • C10M2209/08—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to a carboxyl radical, e.g. acrylate type
  • C10M2209/086—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to a carboxyl radical, e.g. acrylate type polycarboxylic, e.g. maleic acid
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2219/00—Organic non-macromolecular compounds containing sulfur, selenium or tellurium as ingredients in lubricant compositions
  • C10M2219/06—Thio-acids; Thiocyanates; Derivatives thereof
  • C10M2219/062—Thio-acids; Thiocyanates; Derivatives thereof having carbon-to-sulfur double bonds
  • C10M2219/066—Thiocarbamic type compounds
  • C10M2219/068—Thiocarbamate metal salts
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2223/00—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions
  • C10M2223/02—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions having no phosphorus-to-carbon bonds
  • C10M2223/04—Phosphate esters
  • C10M2223/045—Metal containing thio derivatives
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2010/00—Metal present as such or in compounds
  • C10N2010/04—Groups 2 or 12
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2010/00—Metal present as such or in compounds
  • C10N2010/08—Groups 4 or 14
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/06—Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2040/00—Specified use or application for which the lubricating composition is intended
  • C10N2040/04—Oil-bath; Gear-boxes; Automatic transmissions; Traction drives
  • C10N2040/046—Oil-bath; Gear-boxes; Automatic transmissions; Traction drives for traction drives

Definitions

• the present invention relates to grease compositions which can be used in constant velocity joints of drive trains of motor vehicles, or of other gear mechanisms for which greases with a low friction coefficient are sought.
• a transmission or mechanical coupling joint is a mechanical system consisting of several parts which are moveable relatively to each other, or deformable, which allows mutual driving of two rotating parts, the axes of rotation of which occupy variable relative positions during operation. In other words, it is a link which allows transmission of the rotation of one axis to another axis which is moveable relatively to the first.
• a transmission joint is said to be a constant velocity joint if, at any instant, the speeds of rotation of both shafts are equal.
• the movements inside constant velocity joints are complex, with a combination of rolling, sliding and rotations. Wear on the contact surfaces of the components occurs therein, but also significant frictional forces between the surfaces. The wear may result in a failure of the joints and the frictional forces may cause noise, vibrations and jolts in the drive train.
• the greases used in constant velocity joints should have an anti-wear effect and preferentially a low friction coefficient in order to reduce or prevent noises, vibrations and jolts.
• known greases for constant velocity joints frequently contain anti-wear additives, which for example are phosphorus-containing or phosphorus- and sulfur-containing compounds, and friction modifiers, for example organic compounds containing molybdenum, which may have effects on either one of these properties, or even both of them.
• anti-wear additives for example are phosphorus-containing or phosphorus- and sulfur-containing compounds
• friction modifiers for example organic compounds containing molybdenum, which may have effects on either one of these properties, or even both of them.
• solid lubricants, as friction modifiers such as molybdenum bisulfide (MoS 2 ) or tungsten bisulfide (MoS 2 ) or graphite is also known.
• Application FR 2 723 747 discloses high-temperature greases for constant velocity joints comprising mineral and/or synthetic base oils, polyurea thickeners and MoS 2 as a solid lubricant, as well as graphite and at least one organic molybdenum compound, preferentially molybdenum dithiocarbamate.
• the solid lubricants graphite, MoDTC, PTFE, make it possible to reduce the content of expensive solid lubricant MoS 2 , but without however replacing it completely.
• Solid lubricants of the MoS 2 type have a high cost and introduce a high metal content in the formulations, which is not desirable for environmental reasons.
• Nothing in this application suggests the lowering of the metal (Mo) contents of the grease by totally substituting other solid lubricants for the MoS 2 .
• the molybdenum content of the disclosed compositions is of at least of the order of 5,000 ppm. No mention is made of specific molybdenum and graphite contents allowing optimization of the performances of the greases as regards wear and/or friction.
• Nothing in this application either suggests substitution of lithium soaps for polyureas as thickeners.
• the greases thickened with polyureas are technically more complicated to manufacture, in particular because the components used in their manufacture, such as isocyanates and amines, are highly toxic and not very stable upon storage.
• the precautions which have to be taken, make the manufacturing methods more complex and more expensive.
• the availability of the raw materials is also lower as compared with those of greases thickened with metal soaps, in particular with lithium and lithium complex.
• the polyureas are superior in thermal resistance but their thixotropic nature also leads to problems of destructuration under mechanical stress and hardening upon storage. Therefore, technically easier and more economical greases for constant velocity joints will be preferred for formulating greases from non-toxic and non-hazardous materials using fatty acid metal soaps as thickeners.
• Certain commercial greases for constant velocity joints are for example formulated from mineral and/or synthetic base oils, from lithium or lithium complex thickeners, and from molybdenum bisulfide MoS 2 , in an amount of about 3% by mass, which represents a Mo content of about 18,000 ppm. Below this MoS 2 content, the wear and friction performances are insufficient.
• Patent EP 0 708 172 describes a grease with a low friction coefficient for constant velocity joints comprising a base oil, a simple or complex lithium soap thickener, one or several organic components containing molybdenum, of the MoDTC or the MoDTP type, at least one zinc dithiosphosphate, an phosphorus- and sulfur-containing extreme pressure agent free of metal, calcium salt of oxidized waxes, calcium salt of petroleum sulfonate or calcium salt of aromatic alkylsulfonates.
• the disclosed composition examples either have a high molybdenum content (about 8,500 ppm) and/or a high phosphorus content (about 2,000 ppm of phosphorus), which leads to environmental problems.
• Application WO 2007/085643 discloses grease compositions for constant velocity joints, thickened with polyureas, comprising from 0.1 to 5% by weight of WS 2 , and from 0.1 to 5% by weight of zinc dithiophosphate and/or molybdenum dithiocarbamate.
• This application also discloses the possibility of using as an additive in the greases, graphite or MoS 2 .
• graphite (or MoS 2 ) in combination with MoDTC is not recommended, since this combination, according to this application, has a detrimental effect on the anti-wear properties and on the friction coefficient of the greases.
• These greases according to the invention have improved anti-wear properties as compared with known greases for constant velocity joints based on lithium soap.
• the friction properties are equivalent to those of known greases.
• These greases may moreover attain these performances with lower molybdenum and optionally lower phosphorus content than the greases of the prior art.
• the present relation relates to grease compositions comprising:
• the grease compositions according to the invention have a molybdenum content comprised between 100 and 2,800 ppm preferentially comprised between 1,500 and 2,500 ppm, preferentially between 1,700 and 2,300, preferentially between 2,000 and 2,200 ppm.
• the grease compositions according to the invention comprise between 0.5 and 3.0% by mass of graphite, preferentially between 0.7 and 2.0%.
• the grease compositions according to the invention have a Mo/[graphite] ratio, between the molybdenum content in ppm and the percentage by mass of graphite in said compositions, comprised between 1,250 and 1,550, preferentially between 1,300 and 1,500.
• the grease compositions according to the invention comprise phosphorus, at a content of less than 1,500 ppm, preferentially less than 1,200 ppm. According to an embodiment, the grease compositions according to the invention comprise zinc, at a content of less than 1,500 ppm. According to a preferred embodiment, the grease compositions according to the invention are free of solid lubricant MoS 2 .
• the grease compositions according to the invention are free of any polytetrafluoroethylene solid lubricant.
• the grease compositions according to the invention exclusively comprise one or several simple or complex metal salts of fatty acids as a thickener.
• the grease compositions according to the invention comprise at least one simple or complex lithium, sodium, calcium, barium, or titanium soap, either alone or as a mixture, as a thickener.
• the grease compositions according to the invention comprise one or several simple or complex lithium soaps as a thickener.
• the grease compositions according to the invention comprise a mineral base oil (a) and a synthetic base oil (a), preferentially selected from polyalphaolefins.
• the grease composition according to the invention further comprise a polymer (e) preferentially selected from polyisobutenes, olefin copolymers, polymethacrylates, polyalphaolefins, preferentially polyisobutenes.
• the grease compositions according to the invention may further comprise one or several anti-wear and/or extreme pressure additives containing phosphorus and sulfur (f), preferentially selected from zinc dithiophosphates.
• the grease compositions according to the invention have a phosphorus content comprised between 300 and 1,200 ppm, preferentially between 400 and 1,000 ppm, preferentially between 500 and 900 ppm.
• the compositions according to the invention have a zinc content comprised between 500 and 1,400 ppm, preferentially between 600 and 1,300 ppm, preferentially between 800 and 1,000 ppm.
• the grease compositions according to the invention comprise:
• the grease compositions according to the invention comprise:
• the grease compositions according to the invention comprise:
• the grease compositions according to the invention comprise:
• the present invention also relates to the use of grease compositions such as those described above as greases for constant velocity joints of transmissions of automobile vehicles.
• the present invention also relates to one of the constant velocity joints filled with grease compositions as described above.
• the or the other base oil(s) used in the composition according to the present invention can be mineral or synthetic oils originating from the Groups I to V according to classes defined in the API (American Petroleum Institute) classification.
• the mineral base oils according to the invention include all types of bases obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as extraction with a solvent, deasphalting, dewaxing with a solvent, hydrotreatment, hydrocracking and hydroisomerization, hydrofinishing.
• the base oils of grease compositions according to the present invention can also be synthetic oils such as certain esters, silicones, polyalkylene glycols, polybutene, polyalphaolefins (PAO), alkylbenzene, alkyl naphthalene.
• the base oils can also be oils of natural origin, for example alcohol and carboxylic acid esters which may be obtained from natural resources such as sunflower, rapeseed, palm oil, . . . .
• synthetic oils of the polyalphaolefin (PAO) type are present in a combination with mineral oils.
• the polyalphaolefins are for example obtained from monomers having from 4 to 32 carbon atoms (for example octane, decene). Their weight average molecular mass is typically comprised between 250 and 3,000.
• the mixture of base oils is set so that its viscosity at 40° C. according to the ASTM D445 standard is comprised between 30 and 140 cSt, preferentially between 50 and 100 cSt.
• a wide range of light polyalphaolefins such as for example PAO 6 (31 cSt at 40° C.), PAO 8 (48 cSt at 40° C.), or heavy polyalphaolefins, such as PAO 40 (400 cSt at 40° C.), or PAO 100 (1,000 cSt at 40° C.) may be used.
• the greases according to the invention are thickened with fatty acid metal soaps.
• Fatty acid metal soaps may be prepared separately, or in situ during the making of the grease (in the latter case, the fatty acid(s) is(are) dissolved in the base oil, and then the suitable metal hydroxide is added).
• These thickeners are products currently used in the field of greases, which are easily available and inexpensive. They exhibit the best technical compromise by combining both good mechanical properties, good thermal resistance and good resistance to water.
• Fatty acids with a long chain typically comprising from 10 to 28 carbon atoms, saturated or unsaturated, eventually hydroxylated, are preferentially used.
• the long chain fatty acids (typically comprising from 10 to 28 carbon atoms) are for example capric, lauric, myristic, palmitic, stearic, arachidic, behenic, oleic, linoleic, erucic acids and their hydroxylated derivatives.
• 12-hydroxystearic acid is the most well-known derivative of this category, and is preferred.
• These long chain fatty acids generally stem from plant oils, for example palm, castor, rapeseed, sunflower oil, . . . or from animal fats (tallow, whale oil . . . ).
• So-called simple soaps may be formed by using one or several long chain fatty acids. It is also possible to form so-called complex soaps by using one or several long chain fatty acids in combination with one or several carboxylic acids with a short hydrocarbon chain comprising at most 8 carbon atoms.
• the saponification agent used for producing the soap may be a metal compound of lithium, sodium, calcium, barium, titanium, aluminum, preferentially lithium and calcium, and preferably a hydroxide, oxide or carbonate of these metals.
• One or several metal compounds either having the same metal cation or not can be used in the greases according to the invention.
• lithium soaps combined with calcium soaps in a lesser proportion. This has the advantage of improving the water resistance of the greases.
• Metal soaps are used at contents of the order of 5 to 20% by weight, preferentially from 8 to 15% by weight, preferentially from 10 to 12%, typically 11% by weight in the greases according to the invention.
• the amount of metal soap(s) is generally adjusted so as to obtain greases of grade 00, grade 0, grade 1 or grade 2 according to the NLGI classification.
• the greases according to the invention in majority contain fatty acid metal soaps as a thickener. By this is meant that the simple or complex fatty acid metal soaps together represent the highest percentages by weight in the greases according to the invention, as compared with the percentage by weight of the other thickening material.
• the greases according to the invention contain in majority simple or complex lithium soaps as a thickener.
• the simple or complex lithium soaps together represent the highest percentages by weight in the greases according to the invention, as compared with the percentage by weight of the other thickening materials.
• the amount of the simple or complex fatty acid metal soap(s) forms at least 50%, even more preferentially at least 80% by weight based on the total weight of thickening materials, in the grease compositions according to the invention.
• the amount of simple or complex lithium soaps forms at least 50%, even more preferentially at least 80% by weight based on the total weight of thickening materials, in the grease compositions according to the invention.
• the greases according to the invention can contain simple or complex metal soaps of fatty acids as the main thickener, and smaller quantities of other thickeners, such as polyureas, or inorganic thickeners of the bentonite or aluminosilicates type.
• the greases according to the invention are free of polyurea-type thickeners, which are technically more complicated to manufacture, in particular because the components used in their manufacture, such as isocyanates and amines, are very toxic and not very stable upon storage.
• the greases according to the invention exclusively contain simple or complex fatty acid metal soaps as a thickener.
• the greases according to the invention exclusively contain simple or complex fatty acid metal soaps of lithium as a thickener.
• the grease compositions according to the invention contain graphite and molybdenum dithiocarbamate, which gives them improved anti-wear properties as compared with known commercial greases. These properties may be reached with a lower molybdenum content than the one of known greases.
• the molybdenum content of the greases according to the invention is comprised between a 1,000 and 2,800 ppm.
• the Mo/[graphite] ratio between the molybdenum content in ppm and the percentage by mass of graphite in said compositions, is comprised between 1,250 and 1,550.
• the grease compositions also have very good anti-wear and friction properties, equivalent to those of known commercial greases. These good properties are moreover reached with a molybdenum content, and optionally a content of other metal elements such as zinc, or a phosphorus element content, of less than those of known greases.
• solid lubricant additives such as MoS 2 or polytetrafluoroethylene (PTFE) powders.
• PTFE polytetrafluoroethylene
• compositions according to the invention contain molybdenum dithiocarbamates, friction modifier additives which are well known to one skilled in the art.
• molybdenum dithiocarbamate organometallic friction modifiers can for example be molybdenum dialkyldithiocarbamates corresponding to the formula (I):
• X 1 , X 2 , X 3 , X 4 are alkyl chains, preferentially including from 2 to 13 carbon atoms, preferentially from 2 to 6 carbon atoms.
• the amount of MoDTC of the compositions according to the invention is adjusted so that their molybdenum content is comprised between 1,000 and 2,800 ppm, preferentially between 1,500 and 2,500 ppm, preferentially between 1,700 and 2,300, preferentially between 2,000 and 2,200 ppm.
• This content can be measured according to usual techniques: plasma, atomic absorption, X-ray fluorescence.
• MoDTC is not desirable to use as a single additive (anti-wear) in a grease composition. Indeed, it is known that MoDTC requires a minimum activation temperature and the presence of other additives (anti-wear, extreme pressure additives) in order to be efficient. Greases comprising MoDTC without any other anti-wear and/or extreme pressure additive would not be efficient, in particular at a low temperature. In the greases of the prior art, MoDTC is thus combined with phosphorus-containing additives, for example dithiophosphates.
• MoDTC is combined with graphite, which allows production of greases having very good properties as regards wear and friction, with a low molybdenum and phosphorus level.
• Mo content is too low, the anti-wear properties (notably under a high load), will be insufficient for applications to constant velocity joints.
• MoDTC content is too high (to the detriment of graphite), it is seen that the friction performances of the greases are degraded.
• the grease compositions according to the invention contain graphite.
• graphite known for its properties as a solid lubricant, allows reduction in the content of friction modifier and anti-wear additives containing molybdenum (and optionally phosphorus), without providing any metal element, and while maintaining wear and friction properties suitable for the application to constant velocity joints. Entire substitution of these molybdenum additives with graphite is however not desirable, since graphite is not very efficient under a strong load and problems of wear may occur in such greases. Also an increase in the wear is seen when the amount of graphite is too large to the detriment of molybdenum.
• the graphite used in the compositions according to the invention is a micrometric size powder with sizes of particles comprised about between 1 and 15 ⁇ m, and for example a size distribution characterized by a diameter D50 comprised between 3 and 8 ⁇ m, preferentially between 5 and 7 ⁇ m.
• the grease compositions according to the invention preferentially comprise between 0.5 and 3.0% by mass of graphite, preferentially between 0.7 and 2.0%, preferentially between 0.75 and 1.7%, preferentially between 1.0 and 1.5% by mass of graphite.
• the greases according to the invention optionally contain anti-wear and extreme pressure additives containing phosphorus and sulfur, commonly used in the formulation of greases and lubricants.
• anti-wear and extreme pressure additives containing phosphorus and sulfur commonly used in the formulation of greases and lubricants.
• phosphorus and sulfur commonly used in the formulation of greases and lubricants.
• thiophosphoric acid, thiophorous acid, esters of these acids their salts and dithiophosphates, particularly zinc dithiophosphates.
• the zinc dithiophosphates of formula (II) are in particular preferred:
• R 1 , R 2 , R 3 , R 4 are, independently of each other, linear or branched alkyl groups comprising from 1 to 24, preferentially from 3 to 14 carbon atoms or optionally substituted aryl groups including from 6 to 30, preferentially from 8 to 18 carbon atoms.
• compositions according to the invention may be used alone or as a mixture in the grease compositions according to the invention.
• Their percentage by mass in the compositions according to the invention is preferably comprised between 0.5 and 5% by weight, preferentially between 0.7 and 2% by weight, or further between 0.8 and 1.5% by weight based on the total weight of the composition. Their amount will be adjusted so as to observe the limiting contents of the molybdenum and phosphorus elements in the compositions according to the invention.
• the molybdenum (Mo) content of the compositions according to the invention is preferentially comprised between 1,000 and 2,800 ppm, preferentially between 1,500 and 2,500 ppm, preferentially between 1,700 and 2,300, preferentially between 2,000 and 2,200 ppm.
• the phosphorus (P) content of the compositions according to the invention is preferentially less than 1,500 ppm, preferentially less than 1,200 ppm, preferentially comprised between 300 and 1,200 ppm, preferentially between 400 and 1,000 ppm, preferentially between 500 and 900 ppm. This content may be measured according to customary techniques: plasma, atomic absorption techniques.
• the zinc content of the compositions according to the invention is less than 1,500 ppm, preferentially comprised between 500 and 1,400 ppm, preferentially between 600 and 1,300 ppm, preferentially between 700 and, 1200 ppm, preferentially between 800 and 1,000 ppm.
• the lubricant compositions according to the present invention may also contain anti-wear and extreme pressure additives containing phosphorus, such as for example alkyl phosphates or alkyl phosphonates, phosphoric acid, phosphorous acid, mono-, di- and tri-esters of phosphorous acid and of phosphoric acid, and their salts.
• the lubricant composition according to the present invention can also contain anti-wear and extreme pressure additives containing sulfur, such as dithiocarbamates, thiadiazoles and benzothiazoles, sulfur-containing olefins.
• the greases according to the invention can also contain any type of additives suitable for their use, for example antioxidants, such aminated or phenolic antioxidants, antirust agents which may be oxygenated compounds such as esters, copper passivating agents. These different compounds are generally present at contents of less than 1%, or further than 0.5% by mass in the greases.
• the greases according to the invention may also contain polymers (e), for example polyolefins, polyisobutene (FIB), polyethylene, polypropylene, heavy PAOs, olefin copolymers (OCP) for example hydrogenated diene-styrene, polymethacrylates (PMA), in contents generally comprised between 1 and 35%.
• polymers for example polyolefins, polyisobutene (FIB), polyethylene, polypropylene, heavy PAOs, olefin copolymers (OCP) for example hydrogenated diene-styrene, polymethacrylates (PMA), in contents generally comprised between 1 and 35%.
• PIBs of a molar mass comprised between 15,000 and 25,000 Daltons will be used at contents generally comprised between 2 and 15% by mass or between 5 and 10% by mass.
• These polymers are used for improving the cohesiveness of the greases, which thus better resist centrifugation. These polymers also cause better adhesion of the grease to surfaces, and increase the viscosity of the base oil fraction, therefore the thickness of the oil film between the parts subject to friction.
• the greases according to the invention are preferentially made by forming the metal soap in situ.
• One or several fatty acids are dissolved in fraction of the base oil or of the base oil mixture at room temperature. This fraction is generally of the order of 50% of the total amount of oil contained in the final grease.
• the fatty acids can be long acids, comprising from 14 to 28 carbon atoms, in order to form simple soaps, optionally combined with short fatty acids comprising from 6 to 12 carbon atoms, in order to form complex soaps.
• the metal compounds preferentially of the metal hydroxide type are added at a temperature of about 60 to 80° C. It is thus possible to add a single type of metal or combine several metals.
• the preferred metal of the compositions according to the invention is lithium, optionally combined in a lesser proportion with calcium.
• the reaction for saponification of the fatty acids by the metal compound(s) is left to take place at a temperature from about 100 to 110° C.
• the water formed is then evaporated by baking the mixture at a temperature of about 200° C.
• the grease is then cooled by the remaining fraction of base oil.
• the additives are then incorporated at about 80° C. Kneading is then carried out for sufficient time in order to obtain a homogeneous grease composition.
• the consistency of a grease measures its hardness or its fluidity at rest. It is quantified by the penetration depth of a cone with given dimensions and mass. The grease is subject beforehand to kneading. The conditions for measuring the consistency of a grease are defined by the ASTM D217 standard.
• the greases are divided in 9 NLGI (National Lubricating Grease Institute) classes or grades commonly used in the field of greases. These grades are indicated in the table below.
• the greases according to the invention are preferentially greases with consistency comprised between 265 and 430, preferentially between 265 and 385, preferentially between 265 and 340 tenths of a millimeter according to ASTM D217.
• they are of NLGI grade 00, 0, 1 or 2, i.e. their consistency is respectively comprised between 400 and 430, or 335 and 385 or 310 and 340, or 265 and 295 tenths of a millimeter according to ASTM D217.
• Grease compositions containing various additives are prepared from a same base grease comprising mineral and synthetic base oils, thickened with a simple lithium soap prepared from lithine (LiOH.H 2 O), and 12-hydroxystearic acid.
• the composition of the base grease is indicated in Table 1 below.
• base grease commonly designates for one skilled in the art, a grease composition only containing base oils and thickeners, but no additive.
• a polymer for improving cohesiveness and adhesion
• DTPZn anti-wear agent
• various solid lubricants MoS 2 , graphite, MoDTC.
• Grease A is a commercial grease for constant velocity joints
• the greases E, I and J are according to the invention.
• the mass compositions of the greases are given in Table 2, as well as their wear and friction properties.
• the wear properties were evaluated by measuring the wear diameter (in millimeters) after the 4 ball wear test according to the ASTM D2266 standard (1 hour, 40 kg load, 75° C.). According to the STL S71 3100 specification, the greases for constant velocity joints should lead to a wear diameter of less than 50 mm.
• All the greases containing MoDTC combined with graphite have a molybdenum content much lower than that of the commercial grease A, for improved wear performances.
• the greases E and I have the additional advantage of having low friction coefficients, of the order of magnitude of those of the commercial grease A.

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